Method of sizing paper with carboxylic acid anhydride particles and polyamines



United States Patent Cflice 3,445,330 METHOD OF SIZING PAPER WITHCARBOX- YLIC ACID ANHYDRIDE PARTICLES AND POLYAMINES Russell JosephKulick and Edward Strazdins, Stamford, Conn, assignors to AmericanCyanamid Company, Stamford, Conn., a corporation of Maine N Drawing.Continuation-impart of applications Ser. No. 112,781, May 26, 1961, Ser.No. 420,783, Dec. 23, 1964, and Ser. No. 490,636, Sept. 27, 1965. Thisapplication Apr. 28, 1966, Ser. No. 545,872

Int. Cl. D21d 3/00 U.S. Cl. 162-164 4 Claims ABSTRACT OF THE DISCLOSUREPaper is sized with a dispersion of carboxylic acid anhydride particlessuch as stearic anhydride and a cationic polyamine catalyst.

This is a continuation-in-part of our applications Serial Nos. 112,781,420,783 and 490,636 respectively filed on May 26, 1961, Dec. 23, 1964,and Sept. 27, 1965, and now abandoned.

The present invention relates to aqueous dispersions and dry blends ofhydrophobic cellulose-reactive organic paper-sizing carboxylic acidanhydrides and a catalyst which accelerates development of the sizingaction of said anhydride, and the manufacture of sized paper by the useof said compositions. The invention includes the compositions themselvesand methods for their preparation.

Nathansohn U.S. Patent No. 1,996,707 (1935) discloses that well-sizedpaper is obtained when a hydrophobic organic acid anhydride, [forexample, distearic anyhride CH (CH CO OOC(CH CH is added as an anionicdispersion to papermaking cellulose pulp.

However, the process has not achieved commercial success, most probablybecause according to the patent 3 to 6 hours of heating at 80 C. to 110C. are needed to develop the sizing properties of the anhydride.Presentday commercial practice requires that the ultimate sizing ofpaper sizing agents develop more rapidly, and it is generally preferredthat the sizing develop fully while the paper is drying on the machine,i.e., before it is formed into rolls. Present-day machine schedulescomplete the drying step in /2 minute to 3 minutes in this temperaturerange, or slightly above it.

More rapid development of sizing is disclosed by British Patent No.804,504 (1958) which employs as beater additive a dispersion of stearicanhydride and bentonite. The dispersion, however, is anionic and hasevidently not been satisfactory for commercial practice.

The discovery has now been made that dispersions of hydrophobiccellulose-reactive organic anhydrides, when employed in the manufactureof paper as described above, develop their sizing very rapidly when theyhave a dissolved content of a water-soluble cellulose-substantivecationic polymer. In preferred instances these novel compositionsdevelop nearly all of their sizing during the drying stage. The cationicpolymer thus acts as a catalyst or promotor for the anhydride size.

The cationic polymers in the compositions of the present invention arenormally water-soluble and cellulosesubstantive. In every instance atleast a sufiicient amount of the polymer is present to render thedispersed anhydride particles cellulose-substantive, i.e., so that theanhydride particles are substantively adsorbed by cellulose paper-makingfibers in aqueous suspension. This amount of cationic polymer issufiicient to ensure a catalytic effect, i.e., a more rapid developmentof the sizing action of the anhydride than would otherwise be the casewhen 3,445,330 Patented May 20, 1969 the size is applied to cellulosepaper-making fibers and the fibers are heated at 190-250 F.

In general, best results are obtained with cationic polymers ofsubstantial molecular weight which carry a large cationic charge.

Suitable cationic polymers include polyethylenimine and otherwater-soluble substantially linear polymers having a substantialproportion of CH CH NH-- or similar linkages, for example, the 1:1 molarcondensation products of trimethylenediamine with 1,2-dichloroethane or1,3-dichloropropane; the 1:1 molar reaction product of adipic acid withdiethylenetriamine, tetra ethylenepentamine or similarpolyalkylenepolyamines (particularly after reaction with 0.1-1 mole ofepichlorohydrin); and the methylamine-ammonia-epichlorohydrin andsimilar resinous condensation products of Coscia U.S. Patent No.3,248,353; the products formed by partially condensing polyacrylamidewith ethylene diamine. There can also be used polyvinylamine; the 50:2molar ratio acrylamide: diallyldimethyl ammonium chloride copolymer;polyvinyl pyridine and poly-N-methyl pyridinium chloride; andpoly-p-chlorostyrene quaternized with trimethylamine. Suitable polymersinclude water-soluble cationic starch which, while less efiective perunit weight, is less costly, and proteins for example casein and gluerendered soluble by alkali. These solubilized proteins can be added tobeater pulp and are deposited on the fibers by addition of alum; thereaction proceeds rapidly.

The cationic starch referred to above is a water-soluble polymercarrying suflicient cationic amino, quaternary ammonium, or othercationic groups to render the starch as a whole cellulose-substantive.

In general, best results are obtained by use of polymers having amolecular weight in excess of 1,000, and the more highly cationic thepolymer (i.e., the more cationic groups which each polymericmacromolecule contains), the better catalysis it affords. The cationiccharge of any cationic polymer is readily determined by standardlaboratory test in an electrophoretic cell.

The minimum effective amount of the cationic polymer is that whichrenders the dispersed phase cellulose-substantive. This amount isgenerally sufiicient to cause a perceptible catalytic action. Thisamount varies from instance to instance depending chiefly on themolecular Weight of the polymer and its cationic charge and is likewisemost easily found by laboratory trial. The optimum amount is the amountwhich produces the best sizing results.

It is within the scope of the invention to employ a nonionic emulsifyingagent in conjunction with the cationic polymer either to obtain afiner-grained dispersion or to decrease the amount of cationic agentthat otherwise would be necessary.

It has further been found that alum (aluminum sulfate) acts as afortifying agent for the cationic compound. Thus a small amount of alummay be used to replace part of the cationic compound without changingthe waterresistance of the paper ultimately obtained, or may be used toimprove the effectiveness of the cationic size so as to increase thewater-resistance of the paper product.

The alum is added as a dilute aqueous solution separately from thesizing composition, and may be added before, with, or after addition ofthe sizing composition.

The hydrophobic organic paper-sizing anhydrides are those which yieldwater-resistant paper when employed as a size. A convenient way ofscreening acid anhydrides is to form them into 0.2% solutions in avolatile organic solvent, and apply the solution to filter paper. Thefilter paper is impregnated with the solution and is then maintained at225 F. for one hour. Development of water resistance shows that thecompound is a paper sizing anhydride.

The paper-sizing cellulose-reactive anhydrides include the dianhydridesformed from hydrophobic organic carboxylic acids of more than 12 carbonatoms for example myristic, palmitic, oleic, and stearic anhydrides, thecorresponding polymeric anhydrides formed from dicarboxylic acids forexample 1,12-dodecanedicarboxylic acid; and mixed anhydrides for examplestearic acetic anhydride.

The invention does not depend upon the particular way in which thedispersions are prepared. In general it is preferable to employ a methodwherein the acid anhydride (or a mixture of acid anhydrides) isemulsified in water containing an effective amount of a high-efiiciency,cationic emulsifying agent either alone or in admixture with a minoramount of an anionic emulsifying agent (the amount of anionic agentbeing sufiiciently small that the net charge of the particle iscationic), additional cationic agent being subsequently added should theSpecific properties of the paper-making suspension show this to bedesirable. This procedure minimizes consumption of the normally morecostly cationic component while producing a finer-grained emulsion.

The organic paper-sizing acid anhydrides generally have melting pointslower than 95 C. and can, therefore, be emulsified using hot watercontaining an appropriate emulsification agent. The higher meltingagents may be emuslified by high-pressure emulsification above 100 C. orby use of solvents.

It is usually advantageous to pass the emulsion through a homogenizer todecrease the dimensions of the emulsified droplets as much as practical,after which the emulsion is immediately and rapidly cooled to form asolid-inliquid dispersion. The emulsion is a microscopicallyheterogeneous mixture of the paper sizing: acid anhydride droplets in acontinuous aqueous phase. The droplets are predominantly below In indiameter and our experience is that the finer the droplets the moreefficient are the sizing results. The rapid cooling converts the liquiddroplets to solid particles without substantial change in dimensions.

The cationic polymer may be added before, during, or after theemulsification step. When added after emulsification, it may be addedbefore or after the sizing dispersion is cooled.

The solids content of the sizing dispersions as prepared is a matter ofconvenience. The dispersions are advantageously diluted to /2%5% solidsbefore use to ensure uniform distribution of the size through the paperpulp.

The dispersions are stable over a wide pH range and appear to be moststable in the pH range of 3 to 5.

Sized paper is prepared by use of the dispersions of the presentinvention by forming a suspension of cellulosepapermaking fibers inaqueous medium, adding a cationic dispersion of a paper sizing anhydrideas described above, forming the fibers into a water-laid web, and dryingthe web at a temperature between 190 F. and 250 F. In the case of mostpaper this requires between about /2 and 5 minutes.

The size is effective in small amount, and between 0.1% and 0.5% of sizebased on the dry weight of the fibers is generally sufficient.

Best sizing generally results when the pulp has a pH between 5 and 8.

A small amount of alum, up to about 2% of the dry weights of the fibers,may advantageously be added with such polymeric agents. The alum appearsto act as extender for the cationic polymer so as to increase the amountof sizing that would otherwise be produced by the size. The alum may beadded after or with the cationic dispersion, but is preferably added inadvance of the cationic dispersion so that the fibers have an adsorbedcontent of alum before the cationic polymer and the anhydride size areabsorbed thereon.

If desired, the sizing dispersion may also be employed by the tub sizingmethod wherein a water-laid cellulose web is impregnated with the sizingdispersion, after which the web is dried. The presence of cationicmaterial in the dispersion results in more rapid development ofwater-resistance on drying than would otherwise be the case, and herelikewise acts as catalyst.

The invention includes dry blends comprising one (or more than one)paper sizing anhydride and at least sufficient of a water-solublecellulose-substantive cationic polymer to render the anhydridecellulose-substantive after emulsification in water, as shown in theexamples below.

The blends may contain one or more non-ionic dispersing agents to assistemulsification; colloid protectors to stabilize the emulsion;hydrophobic pigments such as titanium dioxide or ultramarine to improvethe appearance of the blend, the emulsion and the paper; and perfumes tomask any odor present.

The blends form sizing emulsions when rapidly agitated with watersufficiently hot to melt the anhydride material therein. The resultingemulsion is usually advantageously homogenized and may be added tobeater pulp While hot.

The agents are most conveniently added to the papermaking fibroussuspension as dilute aqueous solutions so as to facilitate metering andto ensure uniform distribution throughout the suspension.

The invention will be further illustrated by the examples which follow.These examples constitute specific embodiments of the invention and arenot to be construed as limitations thereon.

EXAMPLE 1 The following illustrates the preparation of a cationicdispersion of an organic paper-sizing anhydride according to the presentinvention, utilizing a non-ionic dispersing agent to form an initialsubstantially non-ionic dispersion which is converted to cationiccellulose-substantive form by addition of a water-soluble cationicresin.

To 50 ml. of water at C. containing 2 g. of polyoxyethylene sorbitololeate laurate (Atlox 1045A, a nonionic dispersing agent) are added withrapid stirring 10 g. of molten distearic anhydride. A fluid, creamy,substantially non-ionic dispersion forms.

This is slowly added with rapid stirring to 930 ml. of water at 80 C.containing 10 g. of the water-soluble resin prepared by reacting to aGardner-Holdt viscosity of R, 0.2 mol of tetraethylenepentamine with 0.6mol of epichlorohydrin, as shown in Example 1 of Daniel et al. US.Patent No. 2,595,935 (1952). The resulting emulsion is homogenized hotand is then rapidly cooled to room temperature. The product is acationic cellulosesubstantive dispersion containing 1.0% of distearicanhydride which remains stable for more than two days.

EXAMPLE 2 The following illustrates the preparation of a cellulosesubstantive dispersion of a paper-sizing acid anhydride by means of acationic agent which acts as its own emulsifier.

In 600 ml. of water at 80 C. are dissolved 20 g. of a water-solublecationic starch [starch carrying CH CH N(CH substituents; cf. US. PatentNo. 2,935,436 (1960)] and 10 g. of molten distearic anhydride are slowlyadded with vigorous agitation. The resulting emulsion which contains1.6% by weight of distearic anhydride is homogenized hot in a laboratoryhomogenizer and is then rapidly cooled to room temperature.

EXAMPLE 3 The following illustrates the catalytic effect of watersolublecationic polymers in accelerating the rate at which carboxylic anhydridepaper sizes develop their sizing when they are deposited on cellulosefibers in anhydrous medium, and the fibers are then dried and heatedbriefiy in the range of 190 F. to 250 F.

A sheet of 100 lb. basis weight 50:50 bleached hardwood: bleachedsoftwood water-laid (i.e., untreated) paper is torn in half. One sheet(sheet A) is left untreated as control. The other half (sheet B) isimpregnated with a 0.15% by weight solution of the water-soluble polymerprepared by condensing a 1:1 molar ratio adipic acid:tetraethylenepentamine reaction product with about 0.3 mol ofepichlorohydrin to a point close to but short of gelation. The resultingsheet is dried at 190 F. The other half (sheet B) is not treated and isemployed as control.

Both sheets are immersed together in a 0.2% by weight solution ofstearic anhydride in carbon tetrachloride until they are saturated,after which they are removed and air dried. Since the size was appliedfrom volatile anhydrous medium on removal from the solution, both sheetscontain identical amounts of stearic anhydride (0.15% by weight). Thesheets are then curved by passage for 90 seconds over a laboratory drumdrier having a drum temperature of 230 F.

The amount of sizing which is developed by the anhydride is determinedby applying drops of 20% aqueous lactic acid to the sheets and notingthe length of time during which the drops remain unabsorbed on thesheets. Results are as follows:

Percent Percent stearic Polyamine in Seconds heated Lactic acid Sheetanh. in paper paper at 230 F. sizing, secs.

A 0. None 90 196 B 0.15 0. 15 90 2, 440

From previous experience it is known that the sizin g dereloped by sheetB is in excess of 80% of its ultimate sizing.

Since the only variable in the foregoing procedure is the percent of thepolyamine, the results show in classical fashion that the cationicpolymer exerts a pronounced catalytic effect on the rate at which thestearic anhydride develops its sizing.

EXAMPLE 4 The following illustrates the catalytic effect of a cationicwater-soluble polyamine having a substantial molecular weight and a highcationic charge in accelerating the rate at which carboxylic anhydridepaper sizes develop their sizing when they are deposited on cellulosefibers in aqueous medium and the fibers are then dried and heated in therange of 190 F. to 250 F.

A sheet of the same (100 lb. basis weight) water-leaf paper as is usedfor Example 3 is immersed in a 0.1% by weight water solution of theWater-soluble strongly cationic polyamine formed by reacting a 1:1 molarratio adipic acid:tetraethylenepentamine condensate with 0.3 mol ofepichlorohydrin in water to a point near to but short of gelation. Thepaper is then dried by heating for 1 minute in an oven at 240 F. Theresulting sheet contains 0.148% of its dry Weight of the polyamine. Thesheet is then impregnated by immersion for 10 seconds in an aqueousdispersion containing 0.2% by weight of stearic anhydride in an aqueousmedium containing cationic starch and sodium lignosulfonate asemulsifying agents. The resulting paper contains 0.291% of stearicanhydride based on its dry weight and is placed in a forced draft ovenfor 2 minutes at 230 F.

The sizing of the paper is determined by penescope application of a byweight aqueous lactic acid solution at 100 F. under a 12" head. Thesheet resists penetration by this fluid for more than 7,200 seconds.

In the absence of the polyamine, this sheet would possess substantiallyno resistance to the fluid and would behave as if it were unsized paper.

6 EXAMPLE 5 The procedure of Example 1 is repeated except that 20 g. ofthe urea-formaldehyde-triethylenetetramine resin of U.S. Patent No.2,657,132 is used in place of the amineepichlorohydrin resin employedtherein. A similar emulsion is obtained.

EXAMPLE 6 The procedure of Example 1 is repeated except that as cationicagent there is used 10 g. of the water-soluble diethylenetriamine-adipic acid-epichlorohydrin resin prepared as disclosedin Keim U.S. Patent No. 2,926,154 1960). A similar dispersion isobtained.

EXAMPLE 7 The procedure of Example 1 is repeated using as sizing agentstearic acetic anhydride The agent is prepared by reacting stearoylchloride and glacial acetic acid in diethyl ether solution at 10 C. inthe presence of pyridine as acid acceptor. A similar dispersion isobtained.

EXAMPLE 8 The following illustrates the preparation of a cationicemulsion which yields excellent sizing values and which remainschemically and physically stable for a long time.

To 908 cc. of water at C. containing 30 g. of the dissolved cationicstarch of Example 2 is added 1.5 g. of sodium lignosulfonate (MarasperseN). To this is run in with vigorous agitation 30 g. of molten stearicanhydride. The resulting emulsion is homogenized hot, and rapidlycooled. To the resulting dispersion is then added 0.4 g. of sodiumhydroxide dissolved in a little water.

This process is disclosed and claimed in Savina U.S. Patent No.3,223,543.

EXAMPLE 9 The procedure of Example 8 is repeated except that 10 g. ofnaphthenie anhydride (prepared from petroleum naphthenic acids) is usedin place of the stearic anhydride. A similar dispersion is obtained.

EXAMPLE 10 The procedure of Example 1 is repeated using a water-soluble89:1 weight ratio acrylamidezdiallyl dimethyl ammonium chloridecopolymer as the cationic agent.

EXAMPLE 1 l The following illustrates the rapidity with which thedispersions of the present invention develop their sizing.

An aqueous suspension of beaten 50% bleached sulfite-50% bleachedhardwood pulp at 0.6% consistency is divided into aliquots, and to eachis added a small amount of one of the dispersions described, as shown inthe table below. The pH of the aliquots is then adjusted to 7, thealiquots are gently stirred for a few minutes to permit adsorption ofthe anhydride size, after which the aliquots are made into handsheets ona Noble & Wood handsheet machine at a basis weight of about 200 lbs. per25"/40 x 500 ream.

The handsheets are dried at 250 F. on a laboratory drum drier (twopasses of 1.5 mins. each) and the lactic acid resistance of the sheetsis then determined, using 20% lactic acid solution applied by penescopeunder a 12-inch head at F. These results indicate the amount of sizingwhich is developed by the paper while in the papermaking machine.

The sheets are then cured in an oven for one hour at 220 F. and theirlactic acid resistance determined once again to show the ultimate sizingdeveloped in each instance by the acid anhydride. Results are asfollows.

Sizing 4 Developed Sizing Dispersion Aiter- Percerfiit na Sizinganhydride Cationic agent Drying Oven sizing at curing at developed 250F., 220 F., on Ex. N 0. Name Percent 2 Name 3 Percent 9 3 min. 1 hr.drier 6 1 Distearic 0. 3 'IEPA-epi resin 0. 3 3, 600 3, 600 100 2 do 0.3 Cationic starch 0. 6 2, 500 3, 600 70 3 d0 0 U-G-TETA resin- 2. 0 240320 75 4 do 0. 3 0.3 3, 600 3, 600 100 5 Stearic acetic 0. 3 0.2 420 60070 6 Distearic 0. 2 0. 8 5 3, 600 3, 600 100 7 N aphthemo 0 5 0.2 410550 68 8 Distearic 0 2 0. 75 3, 600 3, 600 100 1 Example number; seetext for details. 1 Based on dry weight of fibers.

3 TEPA=tetraethylenepentamine; epi=epichlorohydrln;U-F-TETA=ureadormaldehyde-triethylenetetramine; DETA=diethylenetriamine; AM-DADM=acrylamide-diallyldimethyl ammoniumchloride.

* Seconds, using lactic acid solution under l2 head. 5 The sizingdeveloped after 1.5 minutes of drying is 510 seconds. 6 All values inexcess of 3,600 seconds are considered equal.

EXAMPLE 12 The following illustrates the effect on sizing of changes inthe amounts of sizing anhydride and cationic resin applied to the pulp.

To 500 cc. of water at 80 C. are added with vigorous stirring 0.3 g. ofgum ghatti, 1.5 g. of the naphthalenesnlfonic acid-formaldehydeemulsifying agent known as Lemar D, and 3 g. of technical grade moltendistearic anhydride containing 6% unreacted stearic acid. The resultingemulsion is homogenized hot and immediately and rapidly cooled.

Aliquots are taken from a well beaten 50:50 bleached sulfite:bleachedhardwood pulp and treated first with the sizing dispersion and then withan aqueous solution of the tetraethylenepcntamine-epichlorohydrin resinof EX- ample 1, in amounts shown in the table below.

The aliquots are formed into handsheets at 100 1b. basis weight x40"/50O ream), dried for three minutes at 250 F. and their lactic acidresistance determined, all by the method of Example 1. Results are asfollows:

Lactic acid resistance 1 developed after Percent cationic Percentdlstearic drying at 250 F. Run No. resin 1 added anhydride added 1 for 3mins.

Control None 0. 3 Instant l 0. 05 0. 3 1, 000 0. 1 0. 3 2, (100 0. 3 0.3 3, 500 0. 6 0. 3 700 1. 0 0. 3 500 0. 3 0. 1 Instant 0. s 0. 2 700 O.3 O 3 3,500 0. 3 0. 5 7, 200

1 On dry weight of fibers.

1 Seconds.

Comparison of run 3 with run 4 illustrates the effect of the presence ofmore than a suitable amount of the cationic polymer.

EXAMPLE 13 The following illustrates the preparation of a substantiallyanhydrous autodispersible sizing mixture comprising an organic papersizing anhydride and a water-soluble anionic dispersing agent. Thedispersing agent is sodium lignosulfonate, and a dry blend is formed of15 g. of this material, 300 g. of a water-soluble cationic starch, and600 g. of crushed stearic anhydride. The mixture is powdered and forms astable dispersion when 8 g. are slowly added to 200 cc. of rapidlyagitated boiling water. The resulting dispersion is immediately cooledto room temperature and is used in the manufacture of sized paper asdescribed in Example 1 with similar results.

EXAMPLE 14 The following illustrates the apparent wet strength possessedby paper of the present invention.

A strip 1" wide and 5" long is cut from paper according to the presentinvention having a content of 0.3% of distearic anhydride and 1% ofcationic starch. The paper is suspended in water having a pH of 8.4(sodium bicarbonate buffer) and temperature of 20 C., under 1 kg. oftension.

The paper is apparently unalfected after 24 hours of the test. A controlstrip of paper containing 1% of alumdeposited fortified gum rosin sizebreaks under the tension in 30 minutes.

EXAMPLE 15 The following illustrates the effectiveness of the cationiccomponents of acid anhydride sizing dispersions according to the presentinvention in the treatment of paper by the tub sizing method. The sizingdispersion used is that of Example 8 except that only 15 g. of cationicstarch 'was used. The dispersion was diluted to 0.38% stearic anhydridecontent by addition of water.

An unsized paper sheet prepared by water-laying an untreated but wellbeaten 50% bleached sulfate:50% bleached hardwood pulp at a basis weightof 200 lbs. per 25" x 40"/500 ream is dried at C. for 3 minutes and isthen immersed for 2 seconds in the sizing dispersion. The sheet ispassed through a press to remove excess (unadsorbed) dispersion and isfound to have picked up 79% of its weight of the dispersion andtherefore contains 0.3% by weight of the anhydride size and half thatamount of the cationic starch.

The sheet is then dried for 3 minutes at C. The lactic acid resistanceof the sheet treated as described above is in excess of 3600 seconds.

EXAMPLE 16 The following illustrates the large-scale preparation andtesting of a cationic distearic anhydride emulsion prepared byemulsification of distearic anhydride by the action of a cationicemulsifying agent in admixture with a minor amount of an anionicemulsifying agent, followed by addition of a supplementary cationicagent so as to form a strongly cationic sizing composition.

An emulsifying medium composed of water having a dissolved content of 5%by weight of cooked cationic starch and 0.6% of sodium lignosulfonate iscontinuously supplied at 75 C. to a centrifugal pump and thence to ahomogenizer. Into the emulsifying medium immediately upstream from thepump is continuously introduced distearic anhydride at 85 C. at a rateequal to 15% of the weight of the medium. The centrifugal pump forms thecomponents into a crude emulsion and the homogenizer produces a stableemulsion. The discharge from the homogenizer is diluted to 3% distearicanhydride content and is simultaneously cooled by introduction of cold(15 C.) water containing 2% by weight of a cationictetraethylenepentamine-adipic acid-epichlorohydrin resin. The resultingdispersion is a pumpable cream.

The cationic resin employed above is prepared by reacting 1 mol ofadipic acid with 1 mol of tetraethylenepentamine at 170 C. to form apolyamidepolyamine, dissolving the polyamidepolyamine in water andreacting it with 0.3 mol of epichlorohydrin as is shown and claimed incopending application Serial No. 281,321 filed on May 17, 1963, byEdward Strazdins and Ronald R. House, now U.S. Patent No. 3,329,657.

The resulting strongly cationic distearic anhydride dispersion issupplied to the fan pump inlet of a paper-making machine which producesfood wrapping paper having a basis weight of 40 lb. per 25" x 40/500ream at a speed of about 1,000 feet per minute. The furnish to themachine is a suspension of well-beaten bleached kraft pulp in waterwhich contains 0.3% alum based on the dry weight of the fibers and whichhas a pH of 6.2. The sizing dispersion is supplied at a rate sufircientto provide 1.5 lb. of distearic anhydride per ton of pulp. In themachine, the water-laid web is dried to about 50% water content on'predrier rolls having surface temperatures from 210 to 240 F., and isthen substantially completely dried by passage over a yankee drierhaving a surface temperature of about 240 F. The dwell time of the paperin the drier section of the machine is about 30 seconds. The paper isformed into a roll immediately on exiting from the machine at 200 F. orhigher.

The sizing of a sample of the paper is determined as produced, by theTAPPI ink fioat test and on a sample of the paper which was given anextra heating at 110 C. for minutes to substantially develop theultimate sizing properties of the distearic anhydride therein. Resultsare as follows:

Percent of ultimate Sizing TAPPI ink developed on Paper sizing secondsmachine As produced 80 After extra heating 85 94. 0

We claim:

aqueous suspension and to accelerate the rate at which said anhydridedevelops its sizing properties when applied to cellulose paper-makingfibers and heated thereon at -250 F., forming said fibers into awater-laid web, and heating said web at a temperature between 190 F. and250 F. only until said web is dry.

2. A process according to claim 1 wherein a small amount of alum up to2% of the dry weight of the fibers is added as extender for saidcationic polymer.

3. A process for the manufacture of sized paper which comprisesimpregnating a water-laid cellulose web with an aqueous dispersion ofhydrophobic cellulose-reactive paper-sizing carboxylic acid anhydrideparticles and a latent catalyst therefor, said catalyst being a normallywater-soluble cellulose-substantive cationic polyamine having amolecular weight in excess of 1,000, and the water soluble saltsthereof, the amount of said polyamine catalyst being at least sufficientto render said anhydride particles substantive to cellulose paper-makingfibers in aqueous suspension and to accelerate the rate at which saidanhydride develops its sizing properties when applied to cellulosepaper-making fibers and heated thereon at 190-250 F., and heating saidweb at a temperature between 190 F. and 250 F. only until said web isdry.

4. A process according to claim 3 wherein the cellulose web is acellulose web having a content of alum.

References Cited UNITED STATES PATENTS 2,099,363 11/1937 Heckert 8116.2X 3,248,353 5/1'966 Coscia 162164 X 2,595,935 5/1952 Daniel et al.162-164 2,935,436 5/1960 Caldwell et al. 162164 3,058,873 10/1962 Keimet al. 162164 3,084,092 4/1963 Arlt 162l58 FOREIGN PATENTS 804,504 11/1958 Great Britain.

OTHER REFERENCES Casey, Pulp and Paper, vol. II, 2nd ed., IntersciencePublishers Inc., New York, 1960, pages 1021 and 1022.

S. LEON BASHORE, Primary Examiner.

U.S. Cl. X.R.

